Dual drum mixer



July 25, 1939.

E. LICHTENBERG ET AL 2,157,243

DUAL DRUM MIXER Filed Ndv. 16, 1957 3 Sheets-Sheqt1 July 25, 1939. E. LlC HTENBERG ,ET AL D AL DRUM MIXER ,3 Sheets-Sheet 3 Filed Nov. 16, 1937 few /1. L/'HTE/VBERG- Use/w? S/IECK- 5 view vertically and longitudinally through I Patented July 2 5, 1939 DUAL DRUM MIXER ,Erlch H. Lichtcnberg and Oscar Sheck, Milwaukee, Wis" assignors to Koehring Company, Mllwaukee, Wis., a, corporation Application November 16, 1937, Serial No. 174,902

6' Claims. (01. 259-165) "Ihe present invention appertains to a special type; of concrete mixing machine known in the art as of dual drum construction by reason of the fact that the concrete aggregates submitted to agitation thereby are first led into a primary mixing drum compartment or chamber wherein they are mixed, and then transferred from said first mixing chamber toa second mixing chamm ber of the drum, from which-latter they are ultivantageously employed today in conjunction with paving or like machines, and is found of high efflciency by reason of the increased capacity afforded by the dual mixing chambers of the drum and the ability to overlap the mixing actions performed in said chambers or compartments.

The improvements of the present invention lie in the provision of a special type of transfer charge-or transfer the aggregates agitated in thefirst mixing chamber to the second mixing chamber, and also adjustable to a position in which the chute will be-inactive or prevent the passing of the agitated material from the first chamber to the second chamber. The means for supporting this transfer chute is-novel in respect to the invention, in that the said means, in the first 'place, is so mounted. and arranged inrespect to the supply or, charging'opening of the drum as not to interfere withthe charging of aggregates into the drum through said opening. In thesecond place, the said supporting means for the transfer chute, so called, is designed so as to comprise a combined bracket and water inlet means for the first or primary mixing chamber of the drum, as will be morefully pointed out hereinafter.

The invention also involves other details of construction and operation,-an understanding of which will be had upon-reference to the accompanying drawings and following description.

In the accompanying drawings:

Figure 1 is a side elevation of the framework of a paving machine of the dual drum type, the

usual boom and bucket orother type of. distributor mounted on the left-hand end of the framework, the traction supporting means and the loading skip being omitted and the drum being shown in section. r i

Figure 2 is a fragmentary enlarged sectional the mately discharged. This type of mixer is adprimaryagitating chamber of the drum, illustrating more fully the mounting means for the transfer chute and the arrangement, of the charging chute in the charging opening of the drum, dotted lines showing such charging chute and a portion of the loading skip bywhich the aggregates to be mixed are supplied to said charging chute.

Figure 3 is a vertical sectional view bringing out more clearly the combined supporting bracket and water inlet structure that carries the turning shaft for the transfer chute.

Figure '4 is a detail perspective view of the transfer chute alone.

Figure 5 is .a horizontal sectional view of the transfer chute showing its disposition in relation to the partition separating the dual mixing chambers of the drum,.and bringing out clearly the manner in which the supporting shaft of the chute is disposed at one side only of the charging opening for the dual drum structure;

also showing the water inlet construction of the supporting bracket for the transfer chute shaft. Figure 6 is a-detail view of the flexible apron member illustrating especially its compositive structure. r

Describing the invention specifically, reference is first made to Figure 1 in which the general framework of the mixing machine is seen to comprise the base frame or chassis. A and the. upper framework includingv upright members B and the top frame members 6. This framework may be mounted upon a tractionbase comprising so-called crawlers or endless traction belt, and at one end of the framework, as upon a bracket I, may be carried a boom and bucket partment 3 and a secondary or charge delivery chamber or compartment 4 Compartments 3 wand 4 are separated-by apartition 5 having a central opening 6 for the passing of the aggregates being agitated, from the chamber 3 to the chamber 4. The drum 2 is longer than the ordinary single drum used in mixing machines of this type, so as to afford a larger volume or capacity for the aggregates to be agitated, and said drum is equipped in both 6f the compartments 3 and l with mixing blades and buckets generally designated at 1. n

, The agitating means I is adapted to raise the aggregate materials being mixed in a particular chamber 3 or 4, so that said materials may be maybe imparted to the crank arm l2, and in ms deposited in the transfer chute 8, as respects the materials in the chamber *3, or deposited in the discharge chute which is located at the discharge gird 2f th drum or the outflow end of the cham- The transfer chute 8 comprises a chute-like body adapted to assume a position inclining from its upper end to its lower end, with its lower end opposite the opening 8 when the chute is adiusted for transfer of materials from the mixing chamber. 3 to the mixing chamber 4. When, however, the chute 8 is turned to a position as illustrated in Figure 2, for instance, the materials being agitated in the chamber 3 will pass backwardly or away from the opening 6 instead of being discharged by the chute into the chamber 4.

The chute 8,.which is somewhat curved in cross section, so as to retain-and convey agitated materials dropping into the same for transfer purposes, is carried by a shaft 8 which is normally inclined in relation to the longitudinal axis of the drum 2, the inner end of the shaft 8, being disposed approximately opposite to the center or axis of the opening 8 and the outer end of the shaft passing through the charging opening in of the drum 2 near the periphery. of the opening and preferably atone side thereof, as distinguished from the upper and lower portions of the opening. Said shaft 8 is carried for free rotationby means of a bracket l8 which is seen best in Figures 2 and 5, said bracket comprising a bearing portion Ilia, through which the shaft 8 passes, and a water inlet section "lb. The section ND is formed with a water inlet end 180, see Figure 5, having lateral disposition, and the lower portion of the section llib is hollow, so

that water may pass freely therethrough below the bearing portion Ilia. At the portion of the section iflb within the drum chamber 3 the casting or body from which the member I8 is made has a horizontally and outwardly curved water outlet portion lld.

Thus it will be seen that the bracket struc-' ture i8 includes not only supporting means for the shaft 8. but a water inlet structure to the inlet lie, to which may be supplied the water from a suitable tank, at the proper time, for mixing with the dry aggregates introduced into the drum 3 by means of a chute ll, shown dottransfer chute 8 from the position of Figure 1 to an inoperative position in which the materials will not be delivered or transferred through the opening 8, any' suitable power device may be employed. In the drawings I have, illustrated a crank arm I! carried by the outer end of the shaft 8, which crank arm is connected with the operating piston rod l3 of an-air ram or similar operating device designated l4. By the admission of pressure fluid'into' the cylinder of the ram- II, or the'controiling ofthe fluid in said member ,itis obvious that a chamber 4.

manner the shaft 8 may be partially rotated to correspondingly impart a half-revolution, more or less, to the chute 8, whereby to shift the latter to and from inoperative and operating transfer positions.

The operation of the invention, according to the above described construction, is very simple. By the use of the loading skip, concrete aggregates in dry condition are hoisted and caused to enter the chamber 3 by means of the chute ll. When mixed a certain period of time in the chamber 3. the shaft 8 is turned to shift the transfer chute 8 to the position of Figure 2.

inclined upper curved portion of the chute 8 and will pass through the transfer openings 8 into the When the materials are in the chamber 4 they will be mixed or agitated in the customary way by means similar to the means 1 in chamber 3, and, after being mixed in the said secondary chamber 4 a sufficient time, by the operation of the discharge chute at the'discharge end of the drum 2 toassume a discharge position, the contents of the chamber 4 may be discharged therefrom.

On the introduction of the dry aggregates into the chamber 3, a suitable water valve will be be moistened at the proper time in the op'era tion of agitating and mixing.

-It is notable that the chute 8 is so mounted that during its rotationit moves only in the space of'the chamber 3 and never protrudes through the outflow or transfer opening 8. In no position assumed by the chute 8 is there any engagement of the chute with the partition 5 which is equipped with the transfer opening 6.

As previously indicated, the chute ll may occupy substantially the entire width of the charging opening 211 of the drum 2 and thus the operative charging area of the chute is reduced very slightly only by the supporting and actuating shaft 8 and its supporting bracket.

It is also notable thatthe inclination of the chute 8 is such that it is designed to transfer the agitated materials in the chamber 3 to the chamber 4 at an inclination substantially in line with the direction of agitation or movement of the materials being agitated in the chamber 4 by the lifting blades and buckets of the latter. On this account resistance by said materials to the movement of the drum, incident to the transfer charging of the chamber 4 is reduced to a minimum. Furthermore, when the transfer chute 8 is inoperative, that is, reversed from its position of Figure- 2, it inclines downwardly and away from the transfer outlet or opening 8 in the partition 3. Under these conditions the agitated materials elevated in the chamber 3 will fall downwards upon the reversed transfer chute I and are scattered or splattered in opposite directions on the curved surface of the chute 8 with a certain degree of inclined movement backwardly toward the charging opening in.

Secured to the partition member 5 adjacent its opening 0 is a flexible apron extending toward the transfer chute I and forming an auxiliary partition member. The apron 28 may be preferably constructed from a plurality of sections II, II, 23, and 34 made from heavy rubber sheeting or like resilient material. he

drum, the said operating shaft extending past individual sections of the apron are connected to the portion by means of bolts and clamping plates 25 and 26, respectively. The apron Ill prevents-the accumulation of coarse materials between the transfer chute 8 and partition 5,

which would otherwise interfere with the proper operation of said chute. I

Having thus described our invention, what we claim as new and desire to secure by Letters Patent of the United States,-is;

1. In a mixing machine of the class described, in combination, a mixing drum having a charging opening at the axis thereof and an outflow opening or passage opposite to the charging opening, a chute for charging materials into the drum, extending from a point exterior to the drum, through said charging opening, and occupying in cross section substantially the whole area in said charging opening, a transfer chute in the drum having a concave upper surface and associated with. the outflow opening or passage, said chute being adapted in an operative position with said concave surface uppermost to cause materials in'the drum chamber to pass through said outflow opening, and a rotatable actuating part for said transfer chute extending through the charging opening of the drum for revolving said chute to inverted position in 'which the under surface of the chute serves as a mixing member, and means to support the said transfer chute wholly upon said rotatable part.

2. In a mixing machine of the class described, in combination, a mixing drum having an opening at one end and adjacent to the axis thereof for passage of materials through such opening, and having anoutflow opening or passage opposite to the first mentioned opening for-permitting outflow or transfer movement of materials mixed in the drum, an invertible chute for trans-' ferring mixed materials in the drum through said outflow opening, and operating means,for said chute consisting of a shaft extending through said first mentioned opening of the drum, and bearing means for supporting said shaft in its proper position relatively to said first mentioned opening, said bearing means comprising a bracket in which theshaft is movably mounted, s'aid bracket being provided withwater inlet means including a passage leading from a point exterior to the drum to a point within the same. a

3. In a mixing machine, in combination, a mixing drum having an opening at one end for passage of aggregate materials therethrough,.a'

relatively stationary chute at said opening, said drum being formed with an outflow opening remote from said first mentioned opening, and the two openings being disposed approximately in line with the axis portion of the drum, a'transfer chute for causing passing of the aggregate materials through the outflow opening and disposed to operate adjacent to said outflow opening, means for supporting and operating said while its outer end extends to a point exteriorto the drum through said first opening, of the said stationary chute and supporting the transfer chute, the stationary chute occupying substantially the entire area of said first opening and the said shaft being dimensioned so as to occupy a relatively small portion of the area of said first drum opening and therefore not materially interfering with the passage of the materials through -the stationary chute, and means external to the drum cooperating with the outer projecting end of the shaft for operating the bination with a drum having a continuous body providing first and second mixing chambers arranged end to end, a partition separating the chambers, the drum having an opening at one end communicating with one of the mixing chambers, and the partition having an opening establishing communication between the two mixing chambers, of a transfer chutaadjacent to the opening of said partition, an aggregate directing chute at said'opening and an operating device reaching from a point exterior to the drum through said end opening and connected to the transfer chute to move the same to and from a position for effecting transfer of the aggregates mixed in one chamber to the other, said device being positioned with respect to said end opening so as to be substantially clear of the 'flow stream of aggregates in the aggregate directing chute to thereby prevent a retarding of themixing operation. r 1.

6. In a dual drum mixing machine, the combination with a drum having-a continuous body providing first and second mixing chambers arranged end to end, a partition separating the chambers, the drum having a charging opening at one end'communicating with one of the mixing chambers, and the partition having an opening establishing communication between the two mixingchambers aforesaid, of a transfer chute adjacent to the opening of said partition, an aggregate directing chute at the charging opening in the end of the drum, and an operating and supporting device for said transfer chute reaching from a point exterior to the drum through said charging opening and connected to the transfer chute to move the same to and from a position for effecting trafisfen of the aggregates mixed in the first chamber to the second chamber, said operating and supporting device being supported adjacent to the periphery of the charging opening in a position substantially clear of the flow stream of the aggrej r gates charged into the drum by said aggregate directing chute and the flow stream of the ag-' gregates the flrstchamber.

lumen 11. LICHTENBERGQ- 0 8cm SHECK.

CERTIFICATE OF CORREGTION., Patent No. ,167,215. 1 July 25, 19 9 ERICH H. LIGHTENBERG, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, sec- I 0nd column, line 29 claim 5, before the word "opening" insert end; and that the' said Letters Patent should be read with this correction therein that the same may conform to the .record. of the case in the Patent Office.

Signed and sealed this 19th day of September, A. D. 1939.

Henry Van Arsdele, (Seal) Acting Commissioner of Patents; 

